The Global Navigation Satellite System (GNSS) accurately tracks the position of a target object on the ground using a network of artificial satellites in space. The GNSS includes the Global Positioning System (GPS) operated by the United States Department of Defense and the European Union's Galileo positioning system (Galileo) in the initial development phase. The GNSS is used in many applications, such as, for example, in positioning of aircraft or shipping vessels and in information/communications technology such as telematics.
GPS is a global navigation satellite system that provides location information using signals from satellites orbiting the earth. GPS was primarily established for military purposes, but since 2000, selective availability (SA, an intentional noise) was removed from the signals making GPS widely available in various fields. Meanwhile, the Galileo positioning system is a global navigation satellite system intended primarily for civilian use. Galileo provides more precise measurement and enhanced signaling than GPS, and it is expected that the Galileo positioning system will be used in various fields in the future. However, the GPS and Galileo positioning systems are complementary to each other, and it is expected that the two systems will co-exist. Therefore, a satellite signal receiver operable in both GPS and Galileo positioning systems is desirable.